FIG. 1 illustrates a prior art gasket G adapted for use in hub and spigot pipe joints. The gasket G comprises an annular body B having inner and outer surfaces, and having a flange F at one end thereof. The outer surface of the annular body B includes a locking bead L comprising a flat outer surface and angularly extending side surfaces. The interior of the annular body B of the gasket G comprises two sealing lips S1 and S2. The sealing lips of the prior art gasket G are relatively thick and relatively large and are, therefore, relatively inflexible.
FIG. 2 illustrates the gasket for hub and spigot pipe joints of the present invention. The gasket of the present invention is characterized by a semi-circular locking bead formed on the outer surface of the annular body comprising the gasket. The gasket of the present invention is further characterized by multiple angularly inwardly-extending sealing lips which are relatively small and relatively thin compared with the sealing lips of the prior art gasket and are, therefore, relatively flexible.
The multiple sealing lips on the inside of the gasket, combined with the locking bead on the outside of the gasket, are the important features of the gasket. The multiple sealing lips on the inside of the gasket allow the joining pressure at the pipe to be greatly reduced without giving up any of the sealing qualities of the prior art gasket. The semi-circular locking bead on the outside of the gasket prevents the gasket from being forced from the hub of the pipe assembly when pressure is applied to the pipe. These features set the present invention aside from other gasket designs.